Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  rcu: create rcu_my_thread_group_empty() wrapper
  memcg: css_id() must be called under rcu_read_lock()
  cgroup: Check task_lock in task_subsys_state()
  sched: Fix an RCU warning in print_task()
  cgroup: Fix an RCU warning in alloc_css_id()
  cgroup: Fix an RCU warning in cgroup_path()
  KEYS: Fix an RCU warning in the reading of user keys
  KEYS: Fix an RCU warning

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b8ad1ea..8f78073 100644 (file)
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -530,6 +530,7 @@ static inline struct cgroup_subsys_state *task_subsys_state(
 {
        return rcu_dereference_check(task->cgroups->subsys[subsys_id],
                                     rcu_read_lock_held() ||
+                                    lockdep_is_held(&task->alloc_lock) ||
                                     cgroup_lock_is_held());
 }
 

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 07db2fe..db266bb 100644 (file)
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -190,6 +190,8 @@ static inline int rcu_read_lock_sched_held(void)
 
 #ifdef CONFIG_PROVE_RCU
 
+extern int rcu_my_thread_group_empty(void);
+
 /**
  * rcu_dereference_check - rcu_dereference with debug checking
  * @p: The pointer to read, prior to dereferencing

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e2769e1..3a53c77 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1646,7 +1646,9 @@ static inline struct cftype *__d_cft(struct dentry *dentry)
 int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
 {
        char *start;
-       struct dentry *dentry = rcu_dereference(cgrp->dentry);
+       struct dentry *dentry = rcu_dereference_check(cgrp->dentry,
+                                                     rcu_read_lock_held() ||
+                                                     cgroup_lock_is_held());
 
        if (!dentry || cgrp == dummytop) {
                /*
@@ -1662,13 +1664,17 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
        *--start = '\0';
        for (;;) {
                int len = dentry->d_name.len;
+
                if ((start -= len) < buf)
                        return -ENAMETOOLONG;
-               memcpy(start, cgrp->dentry->d_name.name, len);
+               memcpy(start, dentry->d_name.name, len);
                cgrp = cgrp->parent;
                if (!cgrp)
                        break;
-               dentry = rcu_dereference(cgrp->dentry);
+
+               dentry = rcu_dereference_check(cgrp->dentry,
+                                              rcu_read_lock_held() ||
+                                              cgroup_lock_is_held());
                if (!cgrp->parent)
                        continue;
                if (--start < buf)
@@ -4555,13 +4561,13 @@ static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,
 {
        int subsys_id, i, depth = 0;
        struct cgroup_subsys_state *parent_css, *child_css;
-       struct css_id *child_id, *parent_id = NULL;
+       struct css_id *child_id, *parent_id;
 
        subsys_id = ss->subsys_id;
        parent_css = parent->subsys[subsys_id];
        child_css = child->subsys[subsys_id];
-       depth = css_depth(parent_css) + 1;
        parent_id = parent_css->id;
+       depth = parent_id->depth;
 
        child_id = get_new_cssid(ss, depth);
        if (IS_ERR(child_id))

diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 03a7ea1..49d808e 100644 (file)
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -122,3 +122,14 @@ void wakeme_after_rcu(struct rcu_head  *head)
        rcu = container_of(head, struct rcu_synchronize, head);
        complete(&rcu->completion);
 }
+
+#ifdef CONFIG_PROVE_RCU
+/*
+ * wrapper function to avoid #include problems.
+ */
+int rcu_my_thread_group_empty(void)
+{
+       return thread_group_empty(current);
+}
+EXPORT_SYMBOL_GPL(rcu_my_thread_group_empty);
+#endif /* #ifdef CONFIG_PROVE_RCU */

diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 9b49db1..19be00b 100644 (file)
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -114,7 +114,9 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
        {
                char path[64];
 
+               rcu_read_lock();
                cgroup_path(task_group(p)->css.cgroup, path, sizeof(path));
+               rcu_read_unlock();
                SEQ_printf(m, " %s", path);
        }
 #endif

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6c755de..0f711c2 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -811,10 +811,12 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
         * enabled in "curr" and "curr" is a child of "mem" in *cgroup*
         * hierarchy(even if use_hierarchy is disabled in "mem").
         */
+       rcu_read_lock();
        if (mem->use_hierarchy)
                ret = css_is_ancestor(&curr->css, &mem->css);
        else
                ret = (curr == mem);
+       rcu_read_unlock();
        css_put(&curr->css);
        return ret;
 }
@@ -2312,7 +2314,9 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 
        /* record memcg information */
        if (do_swap_account && swapout && memcg) {
+               rcu_read_lock();
                swap_cgroup_record(ent, css_id(&memcg->css));
+               rcu_read_unlock();
                mem_cgroup_get(memcg);
        }
        if (swapout && memcg)
@@ -2369,8 +2373,10 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry,
 {
        unsigned short old_id, new_id;
 
+       rcu_read_lock();
        old_id = css_id(&from->css);
        new_id = css_id(&to->css);
+       rcu_read_unlock();
 
        if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
                mem_cgroup_swap_statistics(from, false);
@@ -4038,11 +4044,16 @@ static int is_target_pte_for_mc(struct vm_area_struct *vma,
                        put_page(page);
        }
        /* throught */
-       if (ent.val && do_swap_account && !ret &&
-                       css_id(&mc.from->css) == lookup_swap_cgroup(ent)) {
-               ret = MC_TARGET_SWAP;
-               if (target)
-                       target->ent = ent;
+       if (ent.val && do_swap_account && !ret) {
+               unsigned short id;
+               rcu_read_lock();
+               id = css_id(&mc.from->css);
+               rcu_read_unlock();
+               if (id == lookup_swap_cgroup(ent)) {
+                       ret = MC_TARGET_SWAP;
+                       if (target)
+                               target->ent = ent;
+               }
        }
        return ret;
 }